[RFC PATCH] iommu: add domain->nested

Add domain->nested to decide whether domain is in nesting mode,
since attr DOMAIN_ATTR_NESTING is removed in the patches:
7876a83 iommu: remove iommu_domain_{get,set}_attr
7e14754 iommu: remove DOMAIN_ATTR_NESTING

Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>
---

Nesting info is still required for vsva according to
https://patchwork.kernel.org/project/linux-arm-kernel/patch/20210301084257.945454-16-hch@lst.de/

 drivers/iommu/iommu.c | 8 +++++++-
 include/linux/iommu.h | 1 +
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 808ab70..ba26ad0 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c

@@ -2684,11 +2684,17 @@ core_initcall(iommu_init);
 
 int iommu_enable_nesting(struct iommu_domain *domain)
 {
+	int ret;
+
 	if (domain->type != IOMMU_DOMAIN_UNMANAGED)
 		return -EINVAL;
 	if (!domain->ops->enable_nesting)
 		return -EINVAL;
-	return domain->ops->enable_nesting(domain);
+	ret = domain->ops->enable_nesting(domain);
+	if (!ret)
+		domain->nested = 1;
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(iommu_enable_nesting);
 

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 32d4480..179f849 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h

@@ -87,6 +87,7 @@ struct iommu_domain {
 	void *handler_token;
 	struct iommu_domain_geometry geometry;
 	void *iova_cookie;
+	int nested;
 };
 
 enum iommu_cap {

-- 
2.7.4

On Wed, Jun 16, 2021 at 10:38:02PM +0800, Zhangfei Gao wrote:

This should probably be a bool : 1;

Also this needs a user, so please just queue up a variant of this for
the code that eventually relies on this information.

On 2021/6/16 下午10:44, Christoph Hellwig wrote:

On Wed, Jun 16, 2021 at 10:38:02PM +0800, Zhangfei Gao wrote:

quoted

+++ b/include/linux/iommu.h

@@ -87,6 +87,7 @@ struct iommu_domain {
  	void *handler_token;
  	struct iommu_domain_geometry geometry;
  	void *iova_cookie;
+	int nested;

This should probably be a bool : 1;

Also this needs a user, so please just queue up a variant of this for
the code that eventually relies on this information.

Thanks Christoph

Got it, will do this.